1. Field of the Invention
The present invention relates to a three-dimensional input apparatus for operating a real or virtual object in a three-dimensional space, and more particularly relates to a three-dimensional input apparatus utilizing means of providing the tactile sense to an operator when the operator inputs the instruction.
2. Prior Art
As one of conventional three-dimensional input apparatus, there has been known an apparatus disclosed in Japanese Laid-open No. 4-18626.
FIG. 1 shows a three-dimensional input apparatus 50 which measures the position of a fingertip in three degrees of freedom and which concurrently feeds back the force to the fingertip. The position of the finger 51 is measured by putting strings 57 from a ring 52 worn on the finger 51 to each of four fulcrums 53, 54, 55, 56 and detecting the length of the strings 57.
Further, as shown in FIG. 2, the feedback of the tactile sense to the fingertip is achieved by winding an end of each string 57 around a pulley 59 rotating together with a rotary encoder 58, attaching a weight 60 at the end of the string 57 to set the tension of the string 57 and controlling the strings 57 by an electromagnetic solenoid (not shown).
The conventional three-dimensional input apparatus detects the position of the fingertip in three degrees of freedom from the change in the length of the strings, controls the tension of the strings 57 on the basis of the properties of the virtual object, the position of the fingertip and others and feeds back the tactile sense (force) to the fingertip. However, it cannot rotate in the direction that the ring 52 moves.
Further, as shown in FIG. 2, if two rings 52 are used and each ring is supported by four strings 57, the operation of holding and lifting a three-dimensional object X existing in a virtual space can be operated. However, as shown in FIG. 3, while the operator holds the object or the virtual object X, the rotation around the axis between a thumb 51 and a point finger 61 cannot be performed.
Therefore, in order to solve the above problems, it is an object of the present invention to provide a three-dimensional input apparatus which performs the operations with six degrees of freedom.
A three-dimensional input apparatus according to the present invention comprises an instructing means for instructing three-dimensional position, supporting points provided at least seven locations surrounding the instructing means, for supporting the instructing means so as to be freely moved in the three-dimensional directions and freely rotated around an arbitrary axis, a string connected to each of the supporting points and the instructing means at an end, a measuring means for measuring the length of the string from each of the supporting points to the connected point with the instructing means, and a string tension controlling means for controlling the tension of the string on the basis of the measured result of the measuring means.
Accordingly, when at least seven supporting points and at least seven strings are used, the apparatus can cope with the six degrees of freedom that is the position of three-dimensional position (three degrees of freedom) and the posture (three degrees of freedom).
The measuring means measures the length of the strings from each of the supporting points to the connected point with the instructing means corresponding to the instruction of the instructing means, The string tension controlling means. controls the tension on the basis of the measured result of the measuring means.
Therefore, the tactile sense corresponding to the instruction that is the force feedback is provided to the operator, and owing to the feedback, the operator feels the operation from the change of the force.
In this case, assuming that the string is stable in the initial condition when the same tension acts on the string and that the force vector acting on the instructing means with the string is qi(xcex5R6) (i=1-8), it is preferable to put the string so that the rank of the matrix (xcex5R6X8) formed with the eight vectors qi (i=1-8) is six. Further, the string is preferably made of lightweight member having lower elasticity, e.g., Kevlar (trade name) and fishing line.
According to another aspect of the present invention, a three-dimensional input apparatus comprises an instructing means for instructing the three-dimensional position, constructed to obtain an input by grasping, supporting points provided at least eight locations surrounding the instructing means, for supporting the instructing means so as to be freely moved in the three-dimensional directions and freely rotated around an arbitrary axis, a string connected to each of the supporting points and the instructing means at an end, a measuring means for measuring the length of the string from the supporting point to the connected point with the instructing means, and a string tension controlling means for controlling the tension of the string on the basis of the measured result of the measuring means.
Accordingly, when at least eight supporting points and at least eight strings are used, the apparatus can cope with seven degrees of freedom that is the position of three-dimensional position (three degrees of freedom), the posture (three degrees of freedom) and the grasping (one degree of freedom).
The measuring means measures the length of the strings from each of the supporting points to the connected point with the instructing means corresponding to the instruction of the instructing means. The string tension controlling means controls the tension on the basis of the measured result of the measuring means.
Therefore, the tactile sense corresponding to the instruction that is the force feedback is provided to the operator, and owing to the feedback, the operator feels the operation from the change of the force.
In this case, assuming that the string is stable in the initial condition when the same tension acts on the string and that the force vector acting on the instructing means with the string is qi(xcex5R7) (i=1-8), it is preferable to put the string so that the rank of the matrix (xcex5R7X8) formed with the eight vectors qi (i=1-8) is seven. Further, the string is preferably made of lightweight member having lower elasticity, e.g., Kevlar (trade name) and fishing line.
Here, the instructing means is formed spherical so as to be held by hand and freely expanded and contracted due to the grasping force.
Accordingly, the grasping force can easily be input with at least two fingers. In the case, it is preferable that the instructing means is formed spherical or the like so as to be easily held by hand.
Further, the instructing means may comprise a pair of links crossed to the other and a pin penetrating the center of the links to admit the relative rotation of the links, and a pair of the strings adjacent to the other are connected to both ends of the links.
Accordingly, the grasping force can easily be calculated and the length of the string can be calculated by the four basic operations arithmetic, which improves the speed of calculation and the speed of response.
The first aspect and second aspect of the three-dimensional input apparatus may further comprise a storing means for storing the information of a virtual object which can be recognized by an operator, and a virtual object displaying means for displaying the virtual object in an area where the operator can operate by his hand. The string tension controlling means controls the tension of the string on the basis of measured result of the measuring means and the information of the virtual object loaded from the storing means.
Accordingly, the operator can operate with the same force as the real object while recognizing the virtual object. The operator can experience the realistic operation.
The first aspect and second aspect of the three-dimensional input apparatus may further comprise an operating means for operating an object to be operated, detecting means provided at the operating means, for detecting the contact with the object and an image taking means for taking an image of the object. The string tension controlling means controls the tension of the string on the basis of the measured result of the measuring means and the detected result of the detecting means.
Accordingly, the operator can operate while feeling the tactile sense and while recognizing the object to be operated, which improves the safety and the reliability of the operation.
In the first aspect and second aspect of the three-dimensional input apparatus, each of the supporting points is provided in a shape of a cubic lattice surrounding the instructing means. Accordingly, the force display that is uniform and stable in any directions can be achieved.